Investigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolism
NAMPT (nicotinamide phosphoribosyltransferase) is a universally expressed protein elevated in the serum and synovial fluid of rheumatoid arthritis (RA) sufferers. NAMPT is a rate-limiting enzyme in the biosynthesis of (nicotinamide adenine dinucleotide) NAD+, an essential cellular coenzyme, and has...
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ndltd-bl.uk-oai-ethos.bl.uk-6005532016-02-03T03:18:39ZInvestigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolismEvans, Laura2013NAMPT (nicotinamide phosphoribosyltransferase) is a universally expressed protein elevated in the serum and synovial fluid of rheumatoid arthritis (RA) sufferers. NAMPT is a rate-limiting enzyme in the biosynthesis of (nicotinamide adenine dinucleotide) NAD+, an essential cellular coenzyme, and has also been shown to exert cytokine-like activities as a mediator of innate immunity. However little is currently known of the role of NAMPT in cartilage metabolism. In this thesis, the role and regulation of NAMPT was studied in a variety of model systems. Addition of exogenous (e)NAMPT to fibroblasts in vitro increased MMP-3 release, an effect attenuated by APO866. In vivo studies in a murine arthritis model showed APO866 treatment reduced arthritis index, with a slight reduction in synovial hyperplasia, inflammatory infiltrate and cartilage degradation. In vivo imaging with MMP activatable fluorescent probes showed a reduction in MMP activity in APO866-treated animals compared with placebo. Analyses of archived tissue indicated that APO866 reduced MMP gene expression in affected limbs in a time and dose dependent manner. In a cartilage explant culture system, APO866 significantly attenuated cytokine-mediated proteoglycan (PG) depletion and MMP-2 and -9 release. This was associated with a dose-dependent loss of cell viability. These effects were reversed by co-incubation with NAD+ metabolites NMN and NA, suggesting that cell survival was highly NAD+-dependent, and that cytokine-induced MMP expression could be NAMPT independent. Finally, in vitro studies in RA synovial fibroblasts revealed that intracellular (i)NAMPT is upregulated by cytokine stimulation, with concurrent upregulation of MMPs -1 and -3. The data emphasise the pleiotropic function of NAMPT in health and disease, and suggest a role for extracellular (but not intracellular) NAMPT in cartilage catabolism. Finally, NAMPT inhibition is highlighted as a promising therapeutic strategy for RA.616.7R Medicine (General)Cardiff Universityhttp://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600553http://orca.cf.ac.uk/58335/Electronic Thesis or Dissertation |
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616.7 R Medicine (General) |
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616.7 R Medicine (General) Evans, Laura Investigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolism |
description |
NAMPT (nicotinamide phosphoribosyltransferase) is a universally expressed protein elevated in the serum and synovial fluid of rheumatoid arthritis (RA) sufferers. NAMPT is a rate-limiting enzyme in the biosynthesis of (nicotinamide adenine dinucleotide) NAD+, an essential cellular coenzyme, and has also been shown to exert cytokine-like activities as a mediator of innate immunity. However little is currently known of the role of NAMPT in cartilage metabolism. In this thesis, the role and regulation of NAMPT was studied in a variety of model systems. Addition of exogenous (e)NAMPT to fibroblasts in vitro increased MMP-3 release, an effect attenuated by APO866. In vivo studies in a murine arthritis model showed APO866 treatment reduced arthritis index, with a slight reduction in synovial hyperplasia, inflammatory infiltrate and cartilage degradation. In vivo imaging with MMP activatable fluorescent probes showed a reduction in MMP activity in APO866-treated animals compared with placebo. Analyses of archived tissue indicated that APO866 reduced MMP gene expression in affected limbs in a time and dose dependent manner. In a cartilage explant culture system, APO866 significantly attenuated cytokine-mediated proteoglycan (PG) depletion and MMP-2 and -9 release. This was associated with a dose-dependent loss of cell viability. These effects were reversed by co-incubation with NAD+ metabolites NMN and NA, suggesting that cell survival was highly NAD+-dependent, and that cytokine-induced MMP expression could be NAMPT independent. Finally, in vitro studies in RA synovial fibroblasts revealed that intracellular (i)NAMPT is upregulated by cytokine stimulation, with concurrent upregulation of MMPs -1 and -3. The data emphasise the pleiotropic function of NAMPT in health and disease, and suggest a role for extracellular (but not intracellular) NAMPT in cartilage catabolism. Finally, NAMPT inhibition is highlighted as a promising therapeutic strategy for RA. |
author |
Evans, Laura |
author_facet |
Evans, Laura |
author_sort |
Evans, Laura |
title |
Investigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolism |
title_short |
Investigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolism |
title_full |
Investigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolism |
title_fullStr |
Investigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolism |
title_full_unstemmed |
Investigating the role of nicotinamide phosphoribosyltransferase (NAMPT) in cartilage catabolism |
title_sort |
investigating the role of nicotinamide phosphoribosyltransferase (nampt) in cartilage catabolism |
publisher |
Cardiff University |
publishDate |
2013 |
url |
http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600553 |
work_keys_str_mv |
AT evanslaura investigatingtheroleofnicotinamidephosphoribosyltransferasenamptincartilagecatabolism |
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1718176273420779520 |